From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932866AbWLSSAy (ORCPT ); Tue, 19 Dec 2006 13:00:54 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932871AbWLSSAy (ORCPT ); Tue, 19 Dec 2006 13:00:54 -0500 Received: from liaag2ag.mx.compuserve.com ([149.174.40.158]:48852 "EHLO liaag2ag.mx.compuserve.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932866AbWLSSAx (ORCPT ); Tue, 19 Dec 2006 13:00:53 -0500 Date: Tue, 19 Dec 2006 12:55:06 -0500 From: Chuck Ebbert <76306.1226@compuserve.com> Subject: Re: problem with signal delivery SIGCHLD To: Nicholas Mc Guire Cc: linux-kernel@vger.kernel.org Message-ID: <200612191259_MC3-1-D597-DE30@compuserve.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org In-Reply-To: On Mon, 18 Dec 2006 20:05:35 +0100, Nicholas Mc Guire wrote: > I have a phenomena that I don't quite understand. gdbserver forks and > after setting ptrace (PTRACE_TRACEME, 0, 0, 0); it then execv > (program, allargs); when this child process hits ptrace_stoped (breakpoint > it does the following in kernel space: > > pid > 1 559 5 1242 ptrace_stop > 3 6 2 1242 | do_notify_parent_cldstop > 4 3 2 1242 | | __group_send_sig_info > 5 1 1 1242 | | | handle_stop_signal > 7 0 0 1242 | | | sig_ignored > 8 1 0 1242 | | __wake_up_sync > 8 1 1 1242 | | | __wake_up_common > 10 547 541 1242 | schedule > 10 2 2 1242 | | profile_hit > 13 1 1 1242 | | sched_clock > 15 1 0 1242 | | deactivate_task > 15 1 1 1242 | | | dequeue_task > 19 2 2 0 | | __switch_to > 24 574 574 0 default_idle > So basically child signals -> delayed to next tick -> parent wakes up. What do the first three columns represent? Do you see __wake_up_common() calling default_wake_function()? Can you trace through schedule() and see exactly how it decides to run the idle task instead of the newly-woken parent? Exactly what path does it take? (And which kernel version is this?) -- MBTI: IXTP